COX-2 inhibitors are newly developed drugs for inflammation that block the COX-2 enzyme. Blocking this enzyme impedes the production of prostaglandins that cause the pain and swelling of arthritis inflammation. While COX-2 inhibitors are classified as non-steroidal anti-inflammatory drugs (NSAIDs), most do not have the same problems as other NSAIDs, as they generally block the COX-2 enzyme and not the COX-1 enzyme.
Common examples of NSAIDs which affect both the COX-1 and COX-2 enzymes include aspirin, indomethacin (Indocin), ibuprofen (Motrin), naproxen (Naprosyn), piroxicam (Feldene), and nabumetone (Relafen). These drugs are commonly prescribed medications for the inflammation of arthritis and other body tissues, such as in tendinitis and bursitis. However, all of these medications have side effects. The major common side effects of these NSAIDs are related to the gastrointestinal system. Some 10%-50% of patients are unable to tolerate NSAID treatment because of side effects, including abdominal pain, diarrhea, bloating, heartburn, and dyspepsia. Approximately 15% of patients on long-term NSAID treatment develop ulceration of the stomach and duodenum. Even though many of these patients with ulcers do not have symptoms and are unaware of their ulcers, they are at risk of developing serious ulcer complications such as bleeding or perforation of the stomach.
The annual risk of serious complications with chronic NSAID use is 1%-4%. The risk of complications is higher in elderly patients, rheumatoid arthritis sufferers, patients on anticoagulants such as Coumadin and heparin or cortisone medication, and patients with heart disease or a prior history of bleeding ulcers.
Cyclooxygenase-1 (COX-1) is an enzyme which is normally present in a variety of areas of the body, including sites of inflammation and the stomach. The COX-1 enzyme of the stomach produces prostaglandins that ensure the natural mucus lining which protects the inner stomach. Common anti-inflammatory drugs like aspirin block the function of the COX-1 enzyme along with COX-2. When the COX-1 enzyme is blocked, inflammation is reduced, but the protective mucus lining of the stomach is also reduced, which can cause stomach upset, ulceration, and bleeding from the stomach and intestines.
Cyclooxygenase-2 (COX-2) produces prostaglandins, but the COX-2 enzyme is located specifically in areas of the body that are responsible for inflammation and not in the stomach. When the COX-2 enzyme is blocked, inflammation is reduced. Since the COX-2 enzyme does not play a role in the normal function of the stomach or intestinal tract, medications which selectively block COX-2 do not present the same risk of injuring the stomach or intestines.
Accordingly, the development of new COX-2 inhibitors is desirable as COX-2 inhibitors provide the benefits of reducing inflammation without irritating the stomach.